A secondary battery, that has an excellent charge and discharge cycle characteristics, with a larger capacity, is provided. The secondary battery having a positive electrode, negative electrode and electrolyte, includes a polymer having a repeating unit represented by a formula (1) as an active material of at least one of positive electrode and negative electrode. ##STR00001## According to formula (1), R1, R2, R3 and R4 each independently represents hydrogen atom, substituted or unsubstituted alkyl group, substituted or unsubstituted aromatic hydrocarbons, substituted or unsubstituted hetroaromatic groups, halogen atom, or alkylene group that may be coupled to the ring form either one or both of R1 and R3, R2 and R4.